Mounting means for trim plate of panelboard

ABSTRACT

A panelboard is provided with a lightweight trim plate mounted by means that are totally concealed when the cover of the trim plate is closed. This mounting means includes deflectable rails mounted to the panelboard enclosure and having hook-like formations which snap behind cooperating hook-like stiffening ribs of the trim plate to mount the latter to the enclosure. Adjusting means for operating the rails to a clamping position are concealed when the trim plate door is closed.

United States Patent [191 Meacham [111 3,777,224 [451 Dec. 4, 1973MOUNTING MEANS FOR TRIM PLATE OF PANELBOARD [75] Inventor: James FrankMeacham, Bellmar,

[73] Assignee: I-T-E Imperial Corporation,

Philadelphia, Pa.

[22] Filed: Sept. 5, 1972 [21] App]. No.: 286,143

[52] US. Cl 317/120, 220/24.3, 49/168 [51] Int. Cl. H021) l/04 [58]Field of Search 317/104, 105, 107,

[56] References Cited UNITED STATES PATENTS 3,339,124 8/1967 .lorgensen317/120 3,192,447 6/1965 Kenyeres 317/119 3,618,804 11/1971 Krause3,465,914 9/1969 Pierson, Jr. 317/119 Primary Examiner-Robert K.Schaefer Assistant Examiner-Gerald P. Tolin Attorney-Sidney G. Faber eta1.

[5 7 ABSTRACT A panelboard is provided with a lightweight trim platemounted by means that are totally concealed when the cover of the trimplate is closed. This mounting means includes deflectable rails mountedto the panelboard enclosure and having hook-like formations which snapbehind cooperating hook-like stiffening ribs of the trim plate to mountthe latter to the enclosure. Adjusting means for operating the rails toa clampingpo sition are concealed when the trim plate door is closed.

13 Claims, 11 Drawing Figures ////////Ill \A sum 3 0P4 PATENTED DEC 4I975 PATENTEU saw u BF 4 MOUNTING MEANS FOR TRIM PLATE F PANELBOARD Thisinvention relates to panelboards in general and relates moreparticularly to panelboard trim plates and means for mounting thereof.

Panelboards for domestic and light commercial use have presentedproblems of security, appearance, and installation. That is, apanelboard of this type is installed through a wall opening slightlylarger than the panelboard enclosure. A trim plate is provided to bridgethe gap between the enclosure and the wall opening and to compensate formisalignment between the front of the enclosure and the face of the wallhaving the opening through which the panelboard is installed. The trimplate is usually mounted by screws that are accessible at all times, sothat even if there is a lockable cover mounted to the trim plate and thecover is locked, access may be had to the interior of the panelboards bymerely manipulating the trim plate mounting screws. These mountingscrews also interfere with aesthetic considerations.

Installation of the prior art trim plate has proven to be troublesomewhen the front of the panelboard enclosure is more than slightly out ofline with the exterior wall having the panelboard mounting opening inthat the relatively heavy trim plate mustbe held in position by theinstaller while he attempts to locate con-' cealed tapped holes for themany screws which secure the trim plate in its operative position.

As will hereinafter be seen, the trim plates constructed in accordancewith the instant invention result in reducing weight of the trim plateby utilizing, for the most part, aluminum or lighter gauge steel thanhas been utilized heretofor and at the same time maintaining rigidity.Since the construction does not require welds, numerous other materialsmay be utilized.

In accordance with the instant invention a trim plate is constructed ofpreferably aluminum or relatively light gauge steel and is provided withstiffening ribs at the rear thereof. Some of these ribs are adjacent toopposite edges of the door opening in the trim plate and are shaped, incross section, as outwardly facing hooks that are engaged behindinwardly facing hook-like projections along the free edges of outwardlydeflectable holding rails mounted within the panelboard enclosure. Theserails are biased inwardly toward a trim. plate holding position, but aredeflectable outward during mounting of the trim plate to snap behindtrim plate ribs for engagement and cooperate therewith to hold the trimplate in a preliminary or loose mounting position. Thereafter anadjusting means is operated to move the rails rearward, thereby drawingthe trim plate rearward until movement of the latter is arrested byengagement with the boundary portions defining the wall opening throughwhich the panelboard is installed. The adjusting means consists ofscrews at opposite ends of each rail, with these screws being accessiblefor operation only when the trim plate door is open. Regardless of thelength of each rail only two screws are required therefor.

In one embodiment of this invention, the trim plate and ribs are stampedand bent from a single piece of sheet stock, and in another embodimentof this invention the trim plate is constructed of four elements. Two ofthese elements are identical, with each consisting of a strip having alip along one edge. The other two elements are identical and consist ofa strip-like extrusion having three stiffening ribs. One of these ribsis along one edge of the strip and constitutes a hook-shaped holdingmeans. The other two ribs are bifurcated, with the ends of eachproviding apertures to receive selftapping screws which extend throughthe lips of the other elements for assembling all four elements into aunit.

Accordingly, a primary object of the instant invention is to providesimplified means for installing the trim plate of a panelboard.

Another object is to provide novel constructions of flush-type trimplates for panelboards.

Still another object is to provide novel fastening means to hold thetrim plate of the panelboard, with this fastening means being accessiblefor operation only when the trim plate door is open.

A further object is to provide a lightweight construction for the trimplate of a panelboard.

A still further object is to provide trim plate fastening meansrequiring a minimal number of adjustable elements regardless of thelength of the trim plate.

These objects as well as other objects of this invent,on will becomeinvention apparent after reading the following description of theaccompanying drawings in which:

FIG. 1 is a front elevation of a panelboard constructed in accordancewith teachings of the instant invention.

FIG. 2 is a rear elevation of the trim plate for the panelboard of FIG.1.

FIG. 3 is a side elevation of the trim plate of FIG. 2 looking in thedirection of arrows 3-3 of FIG. 2.

FIG. 4 is a front elevation of the panelboard interior.

FIGS. 5 and 6 are cross sections taken through line 5-5 of FIG. 1,looking in the direction of arrows 5-5. In FIG. 5 the trim plate is inthe process of being mounted, and in FIG. 6 the trim plate is mounted inoperative position.

FIG. 7 is a cross-section taken through line 7-7 of FIG. 4, looking inthe direction of arrows 7-7.

FIG. 8 is a fragmentary side elevation, looking in the direction ofarrows 8-8 of FIG. 7 and showing an adjustable element which mounts aholding rail.

FIG. 9 is a front elevation showing a second embodiment of a trim plateconstructed in accordance with teachings of the instant invention.

FIG. 10 is an exploded perspective showing portions of the trim plate inthe region of arrows 10-10 in FIG. 9.

FIG. 1 l is a fragmentary cross-section taken through line 11-11 of FIG.4 looking in the direction of arrows l l- 1 1.

Now referring to the figures. Panelboard 11 includes panlike rectangularenclosure 12 (FIGS. 4-6) wherein the interior 13 is disposed and securedto rear wall 14. Interior 13 includes line conductor 15 insulated fromenclosure 12 by insulating block 16 and having male stabs 17, 17 engagedby female line terminal stabs 18, 18 of circuit breakers 19, 19 mountedend to end. The load terminal ends of circuit breakers 19, 19 aremechanically secured by cooperation with outward protrusions 21, 21 ofZ-shaped elements secured along the outboard edges of insulator 16. Faceplate 20 is provided with cutouts 23, 23 through which circuit breakeroperating handles 24 extend so as to be manuall-y operable. Screws 22secure base plate 20 to the forward ends of four standoffs 26, whichextend forward from rear wall 14 of enclosure 12.

Disposed along opposite edges of face plate 20 and extending forsubstantially the full length thereof are a pair of clamping rails 30,30 which, as will hereinafter be seen, operatively secure face plate 35at the front of enclosure 12. Each rail 30 is held at opposite endsthereof by a pair of mounting assemblies 31, each including an adjustingscrew 32 whose head is captured at the rear of face plate 20 in therecess 34 formed by depression 33 in face plate forming vertical element36. The head of screw 32 is positioned behind face plate aperture 38 soas to be accessible for operation from the front of face plate 20.

Assembly 31 also includes L-shaped element 41 having threaded aperture42 in leg 43 thereof, with the other leg 44 being generally T-shaped.The other member 47 of assembly 31 includes main leg 48 havingoppositely extending legs 51, 52 at opposite ends thereof. A pair ofscrews 49, 49 fixedly secure member 47 to rail 30. The reduced sectionat the free end of leg 43 extends through slightly oversized aperture 53in leg 51, leg 44 extends through T-shaped aperture 54 of leg 48, andadjusting screw 32 extends through clearance aperture 55 in leg 48.Partly compressed coil spring 56 is mounted on adjusting screw 32 and isdisposed between legs 43 and 48 to bias rail 30 inward and at the sametime permit outward deflection of rail 30, for a reason to behereinafter explained.

Trim plate 35 includes a frame-like flat portion defining interioropening 62 through which circuit breaker handles 24 and adjusting screws32 are accessible when trim plate cover 63 is open. The portions offrame 61 bounding aperture 62 are provided with rearwardly turned lips64-67, with lips 66, 67 being along opposite edges of aperture 62 andhaving rearwardly and outwardly extending formations 68, 69,respectively. At each end of lips 64, 65 there is the combination of anangle bracket 71 and a locating bar 72 both fastened by a screw 73. Thescrews 73 at opposite ends of lip 67 extend into the upper and lowerflanges of door 63 to constitute hinges for the latter. Those screws 73at opposite ends of lip 66 extend beyond lips 64, 65 to provide stopswhich limit rearward movement of door 63 upon closing thereof. Rivets 76secure latch plate 77 to lip 66 at the center thereof where formation 68is cut away. Latch plate 77 is in operative position to be engaged bythe latch portion 78 of key operable locking means 80 mounted to door 63by rivet 79.

In a manner well known to the art, enclosure 12 is inserted throughrectangular opening 82 in wall 83 and is operatively positioned with thefront of enclosure 12 flush or slightly behind exterior surface 84 ofwall 83. Adjusting screws 32 are operated to move rails 30 forward, andthereafter hook-like formations 68, 69 of trim plate lips 66, 67 arepressed against cam surfaces 70 of rails 30 by a rearwardly directedforce exerted against trim plate 35. Since cam surfaces 70 face inward,they act to guide lips 66, 67 to the inboard sides of rails 30. As therearward force is applied to trim plate 35, a camming action takes placebetween surfaces 68, 69, 70, forcing rails 30 to deflect outward, and indoing so springs 56 are further compressed.

When the free ends of hook-like formations 68, 69 pass the free ends ofcam surfaces 70 and move rearward thereof, springs 56 snap rails 30inward, and cam surfaces 70 move in front of hook formations 68, 69 toloosely mount trim plate 35 to enclosure 12. At this time upper bars 72,72 rest against the upper ends of rails 30 to limit downward movement'oftrim plate 35. Door 63 is then opened to gain access to adjusting screws32, and the latter are operated to move assembly 31 rearward, therebydrawing frame portion 61 of trim plate 35 against exterior surface 84 ofwall 83.

To dismount trim plate 35 adjusting screws 42 are operated to move rails30 forward. Thereafter, the servicemans fingers are moved along thefront surface of the face plate 20 and behind first one and then theother of lips 66, 67 to deflect rails 30 outward past the ends of hookformations 68, 69.

In the embodiment hereinbefore described, frame 61 and its stiffeninglips 64-67, as well as hook-like formations 68, 69, are integrallyformed from a single piece of sheet material by a stamping operation. Inanother embodiment of this invention illustrated in FIGS. 9 and 10, theframe-like portion of trim plate 35 is constructed of four elongatedmembers 101-104 secured together by eight self-tapping screws 105.Members 101, 102 are of identical construction with each having amain'flat section 107 having rearwardly extending lip 108 along theinner edge thereof. Members 103, 104 are cut from the same extrusionwhich includes main portion 117 having rearward lip 118 along the inneredge thereof. The rear end of lip 118 is provided with outwardly facinghook-like formation 119 corresponding to hook-like formations 68, 69.Bifurcated longitudinally extending ribs 121, 122 are disposed on therear surface of main section 1 17 and on the inner side of the centerline thereof. The open ends of ribs 121, 122 provide recesses whichreceive self-tapping screws which first pass through clearance apertures123 in lip 108 of member 101. The positions of apertures 123 and ribs121, 122 assure that main sections 107 and 117 are coplanar. Openabledoor 63 in the embodiment of FIG. 9 is hingedly mounted to trim plateframe portion 101-104 in essentially the same manner that cover 63 ishingedly mounted to frame portion 61.

Thus, it is seen that the instant invention provide a novel constructionfor a trim plate used to cover a panelboard enclosure and also providesnovel means whereby installation of the trim plate is simplified. Eventhough this invention has been described in connection with holdingrails that face outward, are biased outward and are deflectable inward,it should now be apparent to those skilled in the art that holding railsmay face inward, they may be biased inward and may be deflectableoutward so long as p ovisions are made for release of modified trimplate hook-like formations and release thereof.

Although in the foregoing preferred embodiments.

have been discussed, many variations and modifications will now becomeapparent to those skilled in the art and it is therefore understood thatthis invention is not limited by the disclosure but only by theappending claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows.

l. A panelboard including a relatively shallow rectangular enclosurehaving an open front; interior means having circuit protector energizingelements; said interior means mounted within said enclosure and securedto the rear wall thereof; said interior means including a removablefront plate through which handles of circuit breakers mounted to saidinterior means extend for manual operation thereof; a trim plate havinga front wall with an interior opening; said opening being smaller thansaid open front and in general alignment therewith, whereby circuitbreaker handles extending through said front plate are accessible foroperation when said trim plate is in its operative position; said trimplate extending beyond all four sides of said enclosure; mounting meansfor securing said trim plate to said enclosure at the front thereof;said mounting means including holding means mounted within saidenclosure; said holding means including at least one elongateddeflectable rail element, biasing means urging said rail element towarda holding position; elongated holding means on said trim plateengageable by said holding means, and said rail element in particular,when the latter is in said holding position, with said rail elementbeing parallel to said elongated holding means; adjustable meansaccessible from inside-said enclosure with said holding means and saidelongated holding means engaged to selectively move said rail toward andaway from said rear wall thereby operating said trim plate toward andaway from said rear wall as required for installation and disassembly ofthe trim plate from the enclosure; said adjustable means beingaccessible for operation through said opening in said trim plate.

2. A panelboard as set forth in claim 1 in which the elongated holdingmeans includesfirst and second rib means on the inside of the trim plateextending generally parallel to opposite boundary edges of said interioropening; said holding means also including another elongated railelement; said elements each having an inwardly turned free edge; each ofsaid rib means having an outwardly turned free edge captured behind saidfree edges of said rail elements.

3. A panelboard as set forth in claim 2 in which the holding means isdeflected outward from said holding position when mounting said trimplate.

4. A panelboard as set forth in claim 3 in which there is a cam meansformed by the cooperation of said elements and said rib means, wherebythe elements are de flected outward when mounting said trim plate.

5. A panelboard as set forth in claim 4 in which the rib means areintegrally formed with said trim plate at the boundary portions of saidinterior opening.

6. A panelboard as set forth in claim 5 in which one of said ribs isextruded together with an elongated side portion of said trim plate andlongitudinally extending stiffening rib means.

7. A panelboard as set forth in claim 5 in which there are rearwardlyextending lips along other boundary portions of said interior opening.

8. A panelboard as set forth in claim 1 in which the holding means ismounted to said front plate and extends forward thereof.

9. A panelboard as set forth in claim 1 in which the rail elements andthe elongated holding means are each generally hook-like incross-section.

10. A panelboard as set forth in claim 1 in which the interior openingis the only aperture in said front wall.

1 l. A panelboard as set forth in claim 10 in which the front wall isvoid of welded connections thereto.

12. A panelboard as set forth in claim 1 in which the trim plate isconstructed of aluminum.

13. A panelboard as set forth in claim 4 in which the cam means includesinwardly and rearwardly inclined surfaces along said inwardly turnedfree edges of said rail elements serving to guide the rib means betweensaid rails.

1. A panelboard including a relatively shallow rectangular enclosurehaving an open front; interior means having circuit protector energizingelements; said interior means mounted within said enclosure and securedto the rear wall thereof; said interior means including a removablefront plate through which handles of circuit breakers mounted to saidinterior means extend for manual operation thereof; a trim plate havinga front wall with an interior opening; said opening being smaller thansaid open front and in general alignment therewith, whereby circuitbreaker handles extending through said front plate are accessible foroperation when said trim plate is in its operative position; said trimplate extending beyond all four sides of said enclosure; mounting meansfor securing said trim plate to said enclosure at the front thereof;said mounting means including holding means mounted within saidenclosure; said holding means including at least one elongateddeflectable rail element, biasing means urging said rail element towarda holding position; elongated holding means on said trim plateengageable by said holding means, and said rail element in particular,when the latter is in said holding position, with said rail elementbeing parallel to said elongated holding means; adjustable meansaccessible from inside said enclosure with said holding means and saidelongated holding means engaged to selectively move said rail toward andaway from said rear wall thereby operating said trim plate toward andaway from said rear wall as required for installation and disasSembly ofthe trim plate from the enclosure; said adjustable means beingaccessible for operation through said opening in said trim plate.
 2. Apanelboard as set forth in claim 1 in which the elongated holding meansincludes first and second rib means on the inside of the trim plateextending generally parallel to opposite boundary edges of said interioropening; said holding means also including another elongated railelement; said elements each having an inwardly turned free edge; each ofsaid rib means having an outwardly turned free edge captured behind saidfree edges of said rail elements.
 3. A panelboard as set forth in claim2 in which the holding means is deflected outward from said holdingposition when mounting said trim plate.
 4. A panelboard as set forth inclaim 3 in which there is a cam means formed by the cooperation of saidelements and said rib means, whereby the elements are deflected outwardwhen mounting said trim plate.
 5. A panelboard as set forth in claim 4in which the rib means are integrally formed with said trim plate at theboundary portions of said interior opening.
 6. A panelboard as set forthin claim 5 in which one of said ribs is extruded together with anelongated side portion of said trim plate and longitudinally extendingstiffening rib means.
 7. A panelboard as set forth in claim 5 in whichthere are rearwardly extending lips along other boundary portions ofsaid interior opening.
 8. A panelboard as set forth in claim 1 in whichthe holding means is mounted to said front plate and extends forwardthereof.
 9. A panelboard as set forth in claim 1 in which the railelements and the elongated holding means are each generally hook-like incross-section.
 10. A panelboard as set forth in claim 1 in which theinterior opening is the only aperture in said front wall.
 11. Apanelboard as set forth in claim 10 in which the front wall is void ofwelded connections thereto.
 12. A panelboard as set forth in claim 1 inwhich the trim plate is constructed of aluminum.
 13. A panelboard as setforth in claim 4 in which the cam means includes inwardly and rearwardlyinclined surfaces along said inwardly turned free edges of said railelements serving to guide the rib means between said rails.